Well , when i alt+tabbed several times and /follow-ed while farming stuff i noticed that those kind of teleports/lags happen, for short and long distances. (so i think there is a server-response fail sometimes)
I also saw real lags, which would have given pvp advantages sometimes or looked like macros.
But im also sure lagmacro users exist or at least existed.
Since im not doing pvp in WSG that often anymore i hardly saw any situation that might have been caused by a macro.
ATM I'd say 10-15% of all cases with lags and weird happenings after that (the number is really low allready) is made by lagmacros, maybe even less.
The use of lagmacro reduced by far since the first ~4-8 weeks when pvp madness reached its climax.
Keep on watching out, its definitely not a myth and the numbers of users shouldnt grow again.